背景回顾：The phytohormone abscisic acid (ABA) promotes plant tolerance to major stresses such as drought, partly by modulating growth through poorly understood mechanisms. 

提出问题：Here, we show that ABA-triggered repression of cell proliferation in the Arabidopsis thaliana root meristem relies on the swift subcellular relocalization of SNF1-RELATED KINASE 1 (SnRK1). 

结果1-正常条件下：Under favorable conditions, the SnRK1 catalytic subunit, SnRK1α1, is enriched in the nuclei of root cells, and this is accompanied by normal cell proliferation and meristem size. Depletion of two key drivers of ABA signaling, SnRK2.2 and SnRK2.3, causes constitutive cytoplasmic localization of SnRK1α1 and reduced meristem size, suggesting that, under nonstress conditions, SnRK2s promote growth by retaining SnRK1α1 in the nucleus. 

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结果2-胁迫条件下：In response to ABA, SnRK1α1 translocates to the cytoplasm, and this is accompanied by inhibition of target of rapamycin (TOR), decreased cell proliferation, and reduced meristem size.  

结果3-抑制出核和促进入核：Blocking nuclear export with leptomycin B abrogates ABA-driven SnRK1α1 relocalization to the cytoplasm and ABA-elicited inhibition of TOR. Furthermore, fusing SnRK1α1 to an SV40 nuclear localization signal leads to defective ABA-dependent TOR repression. 

结论：Altogether, we demonstrate that SnRK2-dependent changes in SnRK1α1 subcellular localization are crucial for inhibiting TOR and root growth in response to ABA. Rapid relocalization of central regulators such as SnRK1 may represent a general strategy of eukaryotic organisms to respond to environmental changes.

 摘 要 

植物激素脱落酸（ABA）可以通过调控生长来促进植物对干旱等胁迫的抗性，但是其分子机制并不清楚。本文中，作者发现在拟南芥根的分生组织中，ABA所诱导的细胞增殖抑制依赖于SnRK1蛋白的快速亚细胞重新定位。在有利的条件下，SnRK1的催化亚单位SnRK1α1在根细胞的细胞核中富集，这通常伴随着正常的细胞增殖和分生组织大小。通过删除两个ABA信号转导途径的关键因子，即SnRK2.2和SnRK2.3，会导致SnRK1α1在胞质中的组成型定位，并减小分生组织的大小，表明在非胁迫条件下，SnRK2能够通过将SnRK1α1滞留在细胞核中，从而促进植物的生长。在响应于ABA时，SnRK1α1会易位到胞质，这通常伴随着TOR的抑制以及细胞增殖减缓、分生组织大小减小。出核抑制剂leptomycin B的处理会消除ABA驱动的SnRK1α1由细胞核易位至细胞质以及ABA诱导的TOR抑制。此外，将SnRK1α1与核定位信号SV40融合，会导致ABA依赖的TOR抑制出现缺陷。总之，本文的研究揭示了依赖于SnRK2的SnRK1α1亚细胞定位变化，对于响应ABA时导致的TOR和根系生长抑制至关重要。SnRK1等核心调控子的快速重新定位可能代表了真核生物响应环境变化的通用策略。